I have a '98 Protege that is very hard to start in the morning. I checked the fuel pressure and it was 36psi. I was told that the Protege spec. for fuel pressure is 63 to 93 psi. Is this correct? I have already changed the fuel filter. I also checked the pressure coming from the fuel pump and it was 85 psi. Could this low reading be caused by the Fuel Pressure Regulator? It's only a $50.00 part and very easy to get to......

 

Here is how to check the pressure regulator. I'm giving the procedure for a 1.5l, because that is the most popular in the US, If you have a 1.8L, let me know, I will send you those instructions, as they are very different and more complicated.

1. Disconnect the negative battery terminal.
2. Remove the air intake hose.
3. Connect the fuel pressure guage between the fuel filter and the main fuel hose.
4. Install the air intake hose.
5. Connect the negative battery cable.
6. Start the engine and let idle.
7. Check the intake manifold vacuum
8. Measure the fuel line pressure. It should be 29-34 psi.
9. If not as specified, do a full inspection of the fuel lines. Check for blockages and check the PRC solenoid. (see later)
10. Disconnect the vacuum from the pressure regulator.
11. Measure the fuel line pressure. It should be 40-45 psi
12. If not as Specified, replace the pressure regulator.

The PRC solenoid.
Unfortunately, there isn't an easy way to describe where this is, or how to test it. On a 1.5, it is a black plastic solenoid, with a small air filter and 2 1/4 inch ports and a plug. It is around the passenger side under the intake. Looking at the solenoid end of the plug, B is the left hand, a is the right hand. With B to ground, The air filter should be passing through to the top port, With continuity between terminals a and b, The flow should be going through the 2 1/4 inch ports.

 

you could pinch the return line at the gas tank and if the pressure goes to operating specs, the regulator is bad.